CRYSTALLIZATION MECHANISMS OF SOME SE100-XTEX GLASSY ALLOYS

The coupling of calorimetric and microscopic techniques shows that the whole crystallization process for some Se100-xTex (x = 10, 15) glassy alloys proceeds by two different mechanisms, which we call. surface a nd bulk, These mechanisms are activated differently depending on the p articular heating rate used and on the temperature of the isothermal h eat treatment chosen. The nucleation frequencies and growth rates were determined from reflection polarized optical microscopy analysis, and a good agreement is found between these experimental results and pred ictions done by the classical nucleation and the normal growth theorie s. The apparent activation energy from the whole crystallization proce ss which is obtained via differential scanning calorimetry is higher f or Se85Te15 than for Se90Te10, and the relation with these values and those obtained from activation energies of nucleation and growth is es tablished, A detailed discussion about the meaning of the different Av rami indexes found is presented.